1. Department of Orthopaedic Surgery, Sakura Medical Center, Toho University, 564-1 Shimoshizu, Sakura, Chiba 285-8741, Japan
2. Nishikawa Orthopedics Clinic, 1-14-2 Ohsakidai, Sakura, Chiba 285-0817, Japan
3. Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuoku, Chiba, Chiba City 260-8670, Japan